The present invention relates to a vacuum interrupter for a high voltage disconnect switch. And, in particular, to a vacuum interrupter assembly for a high voltage disconnect switch composed of a number of vacuum bottles mechanically ganged together in a stacked array and operated by a spring mechanism to interrupt high voltage currents using multiple contact gaps of the multiple vacuum bottles connected in series circuit arrangement. These vacuum bottles are enclosed in an insulating tube made of dielectric material together with the spring mechanism. The insulating member has end members at both ends of the tube to seal off the tube. The total voltage to be interrupted is applied across the series of bottles within the insulating tube. Traditionally this tube is filled with insulating medium of oil, SF6 (sulfur hexafluoride) gas, nitrogen or the use of desiccant to keep the inside of the tube free of water or excess humidity that could cause the bottles electrically to flash over under the high voltage within the tube.
It has been recognized that with an insulating medium such as SF6 gas there is a global warming potential greater than other insulating mediums. Also, the insulating mediums are often pressurized which potentially could cause problems if a leak developed in the insulating tube.
The vacuum bottles typically have the outer container made of ceramic having braze joints. It has been found that problems may arise especially in the braze joints when the bottles are stressed due to tension while the operating mechanism opens and closes the contacts.
U.S. Pat. No. 4,492,835 by John L. Turner, issued Jan. 8, 1985, describes a typical high voltage load interrupter device having a plurality of load interrupter contacts enclosed respectively in axially aligned vacuum bottles, each bottle containing a fixed contact and a second contact movable axially away from the fixed contact to open position and toward the fixed contact to closed position by an actuating mechanism. The bottles are positioned in a tubular housing of dielectric material by a series of stacking pedestals each formed with three equi-angularity spaced radial arms engaging the inner surface of the tubular housing. Each movable contact is normally resiliently biased toward closed position and is moved to open position by a toggle of the actuating mechanism having a pair of arms substantially aligned with the contacts and held in position by springs connected to arms on the operating shaft such that when the operating shaft is rotated by the operating arm, the above-mentioned springs break the toggle, causing the individual contacts to open. A reset spring returns the operating shaft and operating arm to ready position and causes the toggle to return the contacts to their normal closed positions. The Turner patent in order to keep the interior of the interrupter device dry uses nitrogen at a predetermined pressure on the order of 5 PSI.
It is therefore an object of the present invention to develop a vacuum interrupter for a high voltage switch that eliminates the necessity of using the aforementioned insulating mediums, i.e., insulating medium of oil, SF6 (sulfur hexafluoride) gas, nitrogen within the elongated housing or tube of dielectric material that houses the vacuum bottles as described for prior vacuum circuit interrupter's or the necessity of using a desiccant to keep to the inside of the tube free of water or excess humidity that could cause the bottles to electrically flash over under the high voltage within the tube. It is also an object of this invention to develop a vacuum interrupter for a high voltage switch that assures the vacuum bottles are maintained in compression rather then tension to eliminate undesirable stresses on the braze joints of the bottles.